Efficacy and safety of topical acetylcysteine combined with the use of an overcurvature-correcting device in patients with pincer nail deformity: a randomized, vehicle-controlled, investigator-blinded study

Abstract

Background

While pincer nails may be treated using overcurvature-correcting devices, it takes several months to achieve successful outcomes. Nail-softening drugs may reduce the treatment duration required.

Objective

To evaluate the efficacy and safety of treatment with acetylcysteine (AC) gel added to an overcurvature-correcting device, and define the optimal AC concentration.

Methods

In this investigator-blinded study, 70 patients with hallux pincer nail were fitted with an overcurvature-correcting device for 7 days and were randomly assigned to receive a single 24-h administration of a gel containing 10%, 20% or 30% AC or vehicle. Nail improvement was objectively evaluated by calculating the distal narrowed nail width (dNNW) ratio.

Results

All three AC concentrations plus device showed earlier sustained improvement of pincer nails versus vehicle plus device. There was no observable correlation between AC concentration and effectiveness. No clinically problematic adverse events were observed at any AC concentration, and we recommended AC gel at a concentration of 10%.

Conclusions

By adding AC gel application to an overcurvature-correcting device, early and sustained reductions in transverse curvature were produced compared with using a device alone (vehicle control). The dNNW ratio used in this study was an appropriate objective index for evaluating therapeutic effects.

Trial registration:

• jRCT-2080224657

Keywords:

• Acetylcysteine (AC) gel
• distal narrowed nail width
• overcurvature-correcting device
• pincer nail

Acknowledgments

The authors wish to express their gratitude to the patients and their families for their contributions to the study, and to the project members at Maruho Co., Ltd., especially Kanako Ito. We thank Kazutoshi Harada (Tokyo Medical University), Kaoru Takayama (Sokuiku Laboratory), and Tomo Sakiyama for their assistance in performing the third-party morphological evaluations. We also thank Sally-Anne Mitchell, PhD, of McCann Health CMC, Japan, for providing medical writing support, which was funded by Maruho Co., Ltd.

Disclosure statement

MS has received personal fees from Maruho Co., Ltd. AI, AF, and KT are employees of Maruho Co., Ltd.

Data availability statement

The research data underlying this study are subject to restrictions and cannot be shared.

Additional information

Funding

This study was funded by Maruho Co., Ltd.